Does your morning coffee damage your eyesight?

02 November 2021

Author: Kate Green

caffeine eye health

How much caffeine is recommended each day?


We’re now in November which means cooler weather, darker evenings, and trying to keep warm with steaming cups of hot drinks. If you’re a coffee fan, you might also be enjoying the range of seasonal flavoured coffees to be found in cafes across the country. Whether you’re team pumpkin spice latte or you prefer vanilla and caramel shots, the chilly weather usually means that more of us are seeking something warming on a wintry morning.


An impressive 2 billion cups of coffee are drank around the world each day. The NHS recommends that a person consumes no more than 400mg of caffeine a day. Generally, this equates one of the following points:

  • 4 cups of coffee
  • 2 energy drinks
  • 10 cans of cola drink


Caffeine in moderation is usually fine and if you’re somebody who has a couple of cups of coffee a day, you’re unlikely to be doing any damage to your eyes. However, it does also depend on the strength of your coffee. A typical homemade coffee with instant granules contains around 95mg of caffeine, while a Starbucks grande black coffee has 300mg of caffeine. So, if you’re a homemade coffee drinker, you can probably have a lot more of the stuff than if you’re popping to the coffee shop multiple times a day.


Can caffeine consumption boost your eye health?


Before we dive into the negative impacts of coffee and too much caffeine, we have some good news for the coffee lovers out there. There’s plenty of evidence to suggest that caffeine can actually benefit some areas of your eye health!


NHS research has found that moderate coffee consumption (staying within the 400mg guidelines per day) can actually lower your risk of developing diabetes, liver disease, dementia and some types of cancer. Researchers at Harvard also investigated caffeine intake and its correlation to diabetes in 2014. They discovered that participants who increased their caffeine consumption by one cup of coffee each day lowered their risk of type 2 diabetes by 11%. Participants who drank one cup of coffee less per day actually increased their type 2 diabetes risk by 17%. This is certainly good news for any coffee fans! Read about the effects of diabetes on your eyes here.


If you’re wondering about the science behind these claims, then it all comes down to an antioxidant called chlorogenic acid (CGA). This is found in raw coffee beans and it has been discovered to reduce your blood pressure, as well as improving circulation. CGA also “helps to protect the body from a condition called hypoxia, caused by a lack of oxygen”. Your retina (the back of your eye which produces visual images for you to see) can suffer from hypoxia. This is a condition whereby the lack of oxygen results in damaged vision so drinking coffee, in theory, could help with preserving your eye health. Further tests on CGA have also proven that it can stop retinal deterioration. There is good news for the coffee-holics among us after all!


Can too much caffeine cause glaucoma?


Unfortunately, it’s not exclusively positive news when it comes to discussing the effects of caffeine on our vision. One of the biggest eye-related problems that may be brought on by drinking coffee in excess is glaucoma. Glaucoma is a condition whereby your eyesight gradually deteriorates as a result of damage to your optic nerve. The optic nerve is at the back of your eye and it can become damaged by a build-up of pressure inside your eye. This occurs primarily due to issues with the eye’s draining area.


Drinks containing caffeine have been found to increase your blood pressure and with that comes increased eye pressure. Glaucoma is actually the second most common cause of blindness worldwide. It first attacks your peripheral vision but infamously has very few symptoms. If you begin to notice visual changes as a result of glaucoma, it is usually too late to restore your lost vision. Harvard Medical School conducted some research in 2012 which found that people who drink three or more cups of coffee a day are at a higher risk of developing glaucoma.


Although three cups of coffee (depending on their strength) usually would contain no more caffeine than the daily recommended limit of 400mg, it doesn’t mean you should drink that much regularly. Everyone will be affected differently as your caffeine-induced eye health is dependent on your body’s response to caffeine. Everyone processes it differently and some people may find that they are more impacted than others. However, if you have a family history of glaucoma or if you already suffer with high blood pressure, you might want to think about decreasing your coffee intake.


What are the short-term visual effects of too much caffeine?


Increasing your risk of glaucoma by drinking coffee in excess usually occurs over a long period of time. However, there are also short-term effects of drinking too much coffee, including the possibility of a caffeine overdose. Potential symptoms of a caffeine overdose are:

  • Blurry vision (due to a sudden increase in blood sugar levels)
  • Eyelid spasms (myokymia)
  • Dry eyes
  • Nausea
  • Increased heart rate
  • Heart palpitations
  • Seeing flashes of light
  • Hallucinations
  • Feeling thirsty


The most common of these symptoms which people don’t always link to their caffeine intake is dry eyes. Drinking a lot of coffee within a small timeframe can reduce your tear production and, over time, this can lead to chronic dry eye syndrome. Without sufficient lubrication, your eyes are more likely to become inflamed, putting you at risk of corneal abrasions and eye infections.


What’s the key takeaway from this?


If you’ve read this far, chances are you’re a coffee lover who wants to know exactly how much your caffeine intake might be impacting your eye health. You’ll be pleased to have read that there are some positives for your retinal health and diabetes risk. However, when it comes to glaucoma and your risk of dry eye disease, it’s perhaps best to err slightly on the side of caution and stick under that 400mg caffeine daily limit. Fear not – that’s still a couple of homemade cups of the good stuff, or you can have a daily pumpkin spice latte from your favourite coffee shop to get into the seasonal spirit!

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